Last fall, Mandy Patinkin explained why he abruptly left the CBS series “Criminal Minds” in 2007. “It was very destructive to my soul and my personality,” he said about working on a weekly procedural obsessed with the warped thinking of serial killers. “Audiences all over the world use this programming as their bedtime story,” he added as a bit of social commentary. “This isn’t what you need to be dreaming about.”

Looks like many American TV viewers don’t agree with Patinkin, despite the fact that he’s the mensch of the century as Saul on “Homeland.” We kind of, sort of, love serial killers, who surface all over the “dial,” most recently on Fox’s nascent hit, “The Following” and the CW’s “Cult.” Patinkin or no Patinkin, “Criminal Minds” has remained in Nielsen’s weekly Top 15 for five of its eight seasons. Twenty-two years after its release, “The Silence of the Lambs” has become a defining influence on programming, as these series probe the magnetic dynamic between detectives and serial killers. NBC, aware of that trend, is returning to the source on April 4 with “Hannibal,” in which Hugh Dancy’s FBI agent turns to Mads Mikkelsen’s Lecter every week for assistance.

And the serial killers we’re watching aren’t exactly schleps or classic losers. Dexter Morgan, who kills killers on Showtime’s hugely successful “Dexter,” could even be a fashion model for Miami casual chic. The serial killer has become a kind of rock star figure on TV, often charismatic and playful regardless of his brutality. James Purefoy’s Joe Carroll on “The Following” is a former English professor with enough glamour to inspire a cult of younger killers. The January premiere of BBC America’s Victorian procedural “Ripper Street” began with a sightseeing tour of the Ripper’s trail in London, a nod to the fact that he was one of the first serial killers endowed with a form of celebrity. “Ripper Street” isn’t about Ripper so much as those who failed to catch him, but his fame hangs over every episode.

The list of our serial killer fantasies goes on: Serial killers show up regularly on crime procedurals from the “CSI” shows to “Bones,” and a serial killer is the focus of the long arc of CBS’s “The Mentalist,” whose hero still grieves the death of his family at the hands of Red John. “Dark Minds,” an Investigation Discovery reality series, just returned for its second season with a doozy of a “Silence of the Lambs” gimmick: weekly speculation about unsolved serial murders by an anonymous man known as “Raven” who is serving time for a series of murders. And “Bates Motel,” the early story of Norman Bates from “Psycho,” premieres on A&E on March 18. Bates, an icon of twisted Freudian pathology, was Anthony Perkins in Hitchcock’s movie and will be Freddie Highmore on the upcoming series.

Is Mandy Patinkin right — that these gruesome tales aren’t what we need to be dreaming about? I want to say yes, that as a culture we ought to be focusing on more positive fantasies than, as “The Following” has it, gouging out eyes in the name of Edgar Allen Poe. We shouldn’t be elevating these figures, not only the likes of Joe Carroll on “The Following” but also the countless real serial killers such as Charles Manson, Ted Bundy, Jeffrey Dahmer, Aileen Wuornos, John Wayne Gacy, and David Berkowitz who are all endlessly profiled in sensationalized cable biographies. We should ignore them, make them go away.

But my sense of TV, as well as movies and books, is that among its many, many purposes, it can serve as an outlet for our darkest fantasies. TV can provide us with a safe opportunity to process on a subconscious level the scariest behaviors we can imagine — and serial killing, a blend of violence, randomness, and fetishism, is surely up there. Like horror movies, serial killer stories on TV allow us to set free our own murderous thoughts, too — which, on some level, exist in the sanest of people — rather than tamping them down and letting them build up. As Stephen King writes in his essay “Why We Crave Horror Movies,” “anti-civilization emotions don’t go away, and they demand periodic exercise.”

The apocalypses of shows such as “Revolution” and “The Walking Dead” aren’t exactly lullaby material, either. Same with hospital dramas. But they, too, provide the same kind of psychological outlet, a way to let the worst-case scenarios drift through our curious imaginations. The idea of TV programming that is entirely built on triumph and health and “normalcy” is distasteful to me. If you are a student of human behavior, you want to see all facets of it, not just the bright sides.

I’m not defending rampant violence on TV. Gratuitous depictions of violence may or may not lead to cultural desensitivity toward violence in life, but they are a shallow and unsatisfying form of storytelling. I do think that thought-provoking depictions of violence — in, say, the first few seasons of “Dexter,” which were moral conundrums about vigilantism and capital punishment — have a place in our broad range of programming. As long as they are properly rated on the broadcast networks, and put behind pay walls on cable, smart portrayals of violence can be revelatory; without blood, “The Wire” or “The Sopranos” would have lost a lot of their power and impact. As we debate the causes of the Newtown massacre, we need to remember that solely blaming the media is one of those knee-jerk responses that often take attention away from more profound issues.

Of course, badly made and poorly written serial-killer stories on TV are just bad TV. “The Following” has an addictive pace, but it is a mess of crudely drawn clichés with logical leaps that strain the imagination. “Dexter” is now a much diminished product. “Criminal Minds” is a tiresome string of bleak images. They are bedtime stories that do no justice to our nightmares.